1. Field of the Invention
This invention relates generally to methods and apparatus for precision winding single-layer dynamoelectric machine field coils and for inserting the coils in an internally-slotted core member. More particularly, the invention relates to such a method and apparatus in which the gaps between the blades of the insertion apparatus are non-parallel.
2. Description of the Prior Art
Apparatus for inserting dynamoelectric machine field coils into an internally-slotted core member is well known to those skilled in the art, being shown for example in U.S. Pat. No. 3,324,536. Such apparatus conventionally comprises a cylindrical array of elongated, parallel blade elements respectively having distal ends and defining equal-width gaps therebetween which are radially aligned with the centerline of the array. A coil is draped over the distal ends of a group of the blade elements with angled sections of the coil extending through the two gaps on either side of the group of blade elements, the angled sections being respectively joined to end sections disposed within and outside of the array. The array of blade elements is then positioned in the bore of the core member with the blade elements respectively engaging the inner ends of the teeth thereof and the gaps communicating with the winding slots. The coil on the group of blade elements is then pushed into and through the bore of the core member causing the sides of the coil to enter the two slots which communicate with the two gaps on either side of the group of blade elements.
The following U.S. patents known to the present applicant appear to illustrate such inserter apparatus in which the sides of the blade elements which define the gaps therebetween are non-parallel and diverge toward the center of the array of blade elements:
U.S. Pat. No. 3,324,536 (FIG. 9) PA1 U.S. Pat. No. 3,625,261 (FIG. 4) PA1 U.S. Pat. No. 3,828,830 (FIG. 6) PA1 U.S. Pat. No. 3,402,462 (FIG. 2) PA1 U.S. Pat. No. 3,481,372 (FIG. 19G)
However, none of the above-enumerated patents contain any written disclosure of non-parallel gaps and, in fact, in the same drawing figure of each of the above-enumerated patents, some of the gaps are shown as being defined by parallel blade element sides while other gaps are shown as being defined by non-parallel, diverging blade element sides. Furthermore, to the best of the present applicant's knowledge and belief, the apparatus shown in the above-identified patents as actually manufactured by the assignees thereof employed parallel-sided blade gaps and I thus conclude that the showing in those patents of blade gaps having non-parallel, diverging sides is the result of draftmens' inadvertance. The assignee of the present application has manufactured insertion apparatus employing half-round blade elements, however, that apparatus was employed for inserting coils wound with many turns to very fine wire.
Such insertion apparatus is sometimes employed for inserting single layer, precision-wound coils in which the diameter of the wire closely approaches the width of the blade gaps. In the past, such coils have been wound on forms which shape the coils to have angled sections defining the same angle therebetween as the two blade gaps through which such angled sections extend. When such coils are positioned on the blades of the insertion apparatus, the coils define substantially a 90.degree. angle with the blades whereas, for proper insertion, the coils should hang from the blades to define an angle no greater than 45.degree., and preferably smaller, with respect to the blade elements. With such single layer, precision-wound coils defining an angle of nearly 90.degree. with the blades, upon insertion the upper wires of the coils impinge upon the cuffs of the slot liners and must be bent by nearly 90.degree. to align with and enter the stator slots. The force required to bend the coil by nearly 90.degree. frequently damages the cuffs of the slot liners and may flex the blades thus increasing the possibility of wire damage on the lips of the blades. In an effort to eliminate such damage to the slot liner cuffs, prior insertion apparatus has included cuff protector elements which, however, add to the complexity and cost of the apparatus.
Inspection of the geometry involved in inserting single layer, precision-wound coils in which the wire diameter closely approaches the width of parallel-sided blade gaps reveals that while the angled sections of the coil may be positioned in respective radially aligned, parallel-sided slots with the coil disposed in a plane normal to the axis of the array of blades, an attempt to pivot the coil so that it is disposed in a plane defining an acute angle with the blades results in the point at which the projected centerlines of the angled sections of the coil meet when extended to the former horizontal plane of the coil moving radially outwardly from the centerline of the bore toward the periphery of the array so that the projections of the angled sections of the coil define an angle greater than the angle defined by the two slots, thus inhibiting such pivoting of the coil to an inclined position with respect to the blades. In order to overcome this problem, single layer coils have been precision wound with the two angled sections defining an angle therebetween slightly smaller than the angle defined between the respective two parallel-sided blade gaps and with the projected centerlines of the two angled sections meeting at a point spaced radially outwardly from the centerline of the array of blades on the side remote from one end section when the coil is in a plane normal to the centerline of the array. Thus, when the coil is pivoted so as to be inclined with respect to the blades, the projections of the two angled sections of the coil will define the same angle as the angle defined by the two blade gaps, thus permitting the thus inclined coil to be positioned on the blades with the two angled sections extending through the respective two blade gaps. Such coils have been transferred from the coil form on which they are wound to a hand transfer tool of the type shown in U.S. Pat. No. 3,686,735 and then transfered to the inserter blades, the geometry of the pins employed in the hand transfer tool permitting manipulation of the coils following winding to the requisite inclined position.
In recent years, such single layer, precision-wound dynamoelectric machine field coils have been wound and inserted using so-called wind and shed apparatus of the general type shown in U.S. Pat. No. 3,514,837. In an apparatus of that type, the coils are wound on coil forms having a recess formed in the distal end thereof, the recess also communicating with the side portions which shape the angled sections of the coils which later extend through the two blade gaps of the insertion apparatus defining the group of blades around which the coil is draped. As the coil is being wound on the coil form progressing inwardly from the distal end, the ends of the group of blades around which the coil is to be draped are progressively inserted into the coil form recess and the coils are progressively stripped from the coil form onto the blades. With this type of apparatus, since the coils are transferred to the blades at substantially a 90.degree. angle with respect thereto, it is necessary to wind the coils with the angled sections defining the same angle therebetween as the angle defined by the two parallel-sided blade gaps through which the two angled sections extend and thus, it is not possible to wind the coil with the two angled sections defining a smaller angle therebetween than the angle defined by the blade gaps in order to permit inclination of the coils with respect to the blades, as above described.
It is accordingly an object of the invention to provide a method and apparatus of winding single layer, precision-wound dynamoelectric machine field coils and for inserting the same in an internally-slotted stator core member in which the coils may be wound from wire having a diameter closely approaching the width of the blade gaps and nevertheless be inclined with respect to the blades for insertion without damaging the cuffs of the slot liners or flexing the blades.